1. Field of the Invention
The present invention relates to an optical member having lenses and an optical communication module using the same, and more specifically to an optical member usable for plane mounting and an optical communication module using the same.
2. Description of the Related Art
In an optical communication module, a lens is used for coupling light from a light-emitting device to an optical fiber. The lens, normally having a circular shape, is usually disposed at a V-shaped groove formed on a silicon substrate on which the light-emitting device is provided, since the lens should be positioned so as to match the level of the light-emitting device. An example of such an optical communication module is presented in Japanese Unexamined Patent Application Publication No. 2000-12183.
In a configuration in which a lens is disposed on a silicon substrate, the lens has to be fixed at an accurate position relative to the silicon substrate; the position adjustment for such a configuration has been a difficult task. Another problem with the configuration has been that the use of a silicon substrate inhibits miniaturization of the optical communication module. A known example of an optical member, devised to solve the above problems, consists of a rectangular columnar body and lenses provided thereon; the optical member is directly fixed on a substrate on which a light-emitting device is disposed, and receives light from the light-emitting device.
FIG. 4 shows a front view of a conventional optical member. The conventional optical member 50 is formed, as shown in the figure, by disposing a first lens 52 and a second lens 53 both having a convex shape on each end face of a body 51 having a substantially square sectional shape. Since the first and second lenses 52, 53 are disposed so that their center positions 60 are collinear, and coincident with the center position of each end face of the body 51, whichever side face of the body 51 becomes the underside, the height of the center positions 60 of the first and second lenses 52, 53 is maintained constant.
Even in this case, however, a deviation in the height of the light emitting point of a light-emitting device occurs, so it becomes necessary to adjust the height of the center positions 60 of the first and second lenses 52, 53 to match the height of the light emitting point of the light-emitting device. The height of the rectangular columnar body 51 is adjusted by shaving the side face thereof or by disposing a height adjustment spacer, which is a time-consuming job and becomes a factor of cost up.